In recent years, a terminal device such as a smartphone, a tablet terminal, or a personal computer which includes a touch panel display as an input/output device has been rapidly become popular. The terminal device of this type uses an operating tool such as a finger of a user and a stylus pen to select an object such as a document and an image displayed on the touch panel display.
For example, a document display device described in Patent Literature 1 below has been known as a technique to select a text displayed on the touch panel display. The document display device can select a range of the text displayed on the touch panel display by moving a finger in a desired direction while the finger has contact with the touch panel display.